- •Chromatography
- •Manual chromatography methods
- •Automated chromatographs
- •Chromatograph detectors
- •Measuring species concentration
- •Industrial applications of chromatographs
- •Chromatograph sample valves
- •Improving chromatograph analysis time
- •Introduction to optical analyses
- •Dispersive spectroscopy
- •Non-dispersive Luft detector spectroscopy
- •Luft detectors
- •Filter cells
- •Gas Filter Correlation (GFC) spectroscopy
- •Laser spectroscopy
- •Fluorescence
- •Chemiluminescence
- •Analyzer sample systems
- •Safety gas analyzers
- •Oxygen gas
- •Lower explosive limit (LEL)
- •Carbon monoxide gas
- •Chlorine gas
- •Review of fundamental principles
- •Machine vibration measurement
- •Vibration physics
- •Sinusoidal vibrations
- •Vibration sensors
- •Monitoring hardware
- •Mechanical vibration switches
- •Review of fundamental principles
- •Electric power measurement and control
- •Introduction to power system automation
- •Electrical power grids
- •Interconnected generators
- •Circuit breakers and disconnects
- •Reclosers
- •Electrical sensors
- •Potential transformers
- •Current transformers
- •Transformer polarity
- •Instrument transformer safety
- •Instrument transformer test switches
1868 |
CHAPTER 23. CONTINUOUS ANALYTICAL MEASUREMENT |
23.12.5Chlorine gas
Chlorine (Cl2) gas is a strong-odored, toxic gas used as a biological disinfectant, bleaching agent, and as an oxidizer in many industrial processes. Colorless in low concentrations, it may appear green in color when mixed in very high concentrations with air. Chlorine is highly reactive, presenting a distinct hazard to mucus membranes (eyes, nose, throat, lungs) by creating hypochlorous acid (HOCl) and hydrochloric acid (HCl) upon contact with water:
Cl2 + H2O → HOCl + HCl
The following table correlates levels of chlorine gas concentration in ambient air with degree of hazard. Note the unit of measurement for chlorine concentration in air – parts per million (ppm). Bear in mind that one part per million is equivalent to just 0.0001 percent:
Concentration in air |
Hazard |
1 ppm to 3 ppm |
Mild mucus membrane irritation |
|
|
5 ppm to 15 ppm |
Upper respiratory tract irritation |
30 ppm |
Immediate chest pain, cough, and di culty breathing |
|
|
40 ppm to 60 ppm |
Toxic pneumonitis and pulmonary edema |
430 ppm |
Lethal over 30 minutes |
|
|
1000 ppm (0.1%) |
Lethal within a few minutes |
Water and wastewater treatment operations frequently67 use chlorine for disinfection of water. Pulp mills use either chlorine or chlorine compounds as a bleaching agent to whiten wood pulp.
67Some water treatment facilities use powerful ultraviolet lamps to disinfect water without the use of chemicals. Some potable (drinking) water treatment plants use ozone gas (O3) as a disinfectant, which is generated on-site from atmospheric oxygen. A disadvantage to both chlorine-free approaches for drinking water is that neither one provides lasting disinfection throughout the distribution and storage system to the same degree that chlorine does.
23.12. SAFETY GAS ANALYZERS |
1869 |
Chlorine may be generated on site by the electrolytic decomposition of salt (sodium chloride – NaCl), or delivered in cylindrical pressure vessels in liquid form as shown here at a large wastewater treatment facility: